From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B8CEFC77B61 for ; Mon, 10 Apr 2023 13:53:16 +0000 (UTC) Received: from [127.0.0.1] (helo=sfs-ml-1.v29.lw.sourceforge.com) by sfs-ml-1.v29.lw.sourceforge.com with esmtp (Exim 4.95) (envelope-from ) id 1plrxL-0008MQ-Os; Mon, 10 Apr 2023 13:53:14 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1plrxK-0008MC-LB for linux-f2fs-devel@lists.sourceforge.net; Mon, 10 Apr 2023 13:53:13 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: Subject:From:References:Cc:To:MIME-Version:Date:Message-ID:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=7IjlcpX2/Yv5c+wHLxJ5k8LiVyvP2Y6HlvOQiYpJPeM=; b=BOzHt66QtaFiGrko9Fldo30Q5w mmxUnpZvAvs3r5yK9g3n8M+dGfJOcTFkJUtVTLvZgNbUBSXgv7FA+ZxzmRnQH2tMLT49Jfv4DHMeg lbgDOEL2YJVgHMA+hd6E8+ZUnJRAbX76bLLj9BpS7GW3UHIPfoKr9vwXwdDo/or7rI/w=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:Subject:From: References:Cc:To:MIME-Version:Date:Message-ID:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=7IjlcpX2/Yv5c+wHLxJ5k8LiVyvP2Y6HlvOQiYpJPeM=; b=FcaL/c7xYqm8IX4BMk1Ve9iXrJ mqKJ7rAIZxN4tbYnhaUuZOGpRm/2z0pqxTnBKrWlKUxk0LJRTOof/2f65/DCt6bkVOONfWA/9IaRQ xfKKNp1KWV/4bh09bSE1yWy2E4GVtw9qB9ITEOCAoc3i3Uej+zTtjCprOMC7EfSE79RM=; Received: from dfw.source.kernel.org ([139.178.84.217]) by sfi-mx-1.v28.lw.sourceforge.com with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.95) id 1plrxD-002wIr-TY for linux-f2fs-devel@lists.sourceforge.net; Mon, 10 Apr 2023 13:53:13 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B3D9E60ED8 for ; Mon, 10 Apr 2023 13:52:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 861BCC433D2; Mon, 10 Apr 2023 13:52:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1681134777; bh=MiBRI1IjJJKvf3dOcpSwiYgL1iNNZCu/5VtsQEm9a1Q=; h=Date:To:Cc:References:From:Subject:In-Reply-To:From; b=khoEVsj5SJ+iGxEz4qgNP57tIqNFyTUdFKRgnRszpdrkbit+r+E0sSSUuiwc/0qbf XqtwtXWF75to1/+aQjRmgf16yaY8DqJhrjHpDcIDFYXfyxwIpNdddTV4PffGZ1uzRW 3F2i/HEf7o+MlvKnUvjQr56DyxtZ1Qayv2lskB2gr54+rxfJCHeJ87el/Ub5jQ5E/t nR9xhoAA1Ajuug6/RbuhACpYWtcQ2JO8tQxOcDF6MPO5cLCNVmGJ9ueKRTaU+xKm93 f9D7EaGHUjG3AHbN65LvE44rAOiXwLpLw24TvoQt7RoZ5t0WR3OX783FtzHT51wpmt SBO3gESRtT/Sw== Message-ID: Date: Mon, 10 Apr 2023 21:52:52 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Content-Language: en-US To: Jaegeuk Kim References: <20230324071028.336982-1-chao@kernel.org> From: Chao Yu In-Reply-To: X-Headers-End: 1plrxD-002wIr-TY Subject: Re: [f2fs-dev] [PATCH] f2fs: fix to trigger a checkpoint in the end of foreground garbage collection X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On 2023/4/5 23:55, Jaegeuk Kim wrote: > On 04/05, Chao Yu wrote: >> On 2023/4/5 5:39, Jaegeuk Kim wrote: >>> Can we do like this? >>> >>> From 9a58f0e59364241aa31b555cfe793d278e39b0dc Mon Sep 17 00:00:00 2001 >>> From: Jaegeuk Kim >>> Date: Tue, 4 Apr 2023 14:36:00 -0700 >>> Subject: [PATCH] f2fs: do checkpoint when there's not enough free sections >>> >>> We didn't do checkpoint in FG_GC case, which may cause losing to reclaim prefree >>> sctions in time. >>> >>> Fixes: 6f8d4455060d ("f2fs: avoid fi->i_gc_rwsem[WRITE] lock in f2fs_gc") >>> Signed-off-by: Chao Yu >>> Signed-off-by: Jaegeuk Kim >>> --- >>> fs/f2fs/gc.c | 24 +++++++++++------------- >>> 1 file changed, 11 insertions(+), 13 deletions(-) >>> >>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c >>> index 56c53dbe05c9..f1d0dd9c5a6c 100644 >>> --- a/fs/f2fs/gc.c >>> +++ b/fs/f2fs/gc.c >>> @@ -1806,6 +1806,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control) >>> }; >>> unsigned int skipped_round = 0, round = 0; >>> unsigned int upper_secs; >>> + bool stop_gc = false; >>> trace_f2fs_gc_begin(sbi->sb, gc_type, gc_control->no_bg_gc, >>> gc_control->nr_free_secs, >>> @@ -1876,19 +1877,15 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control) >>> (gc_type == FG_GC) ? sec_freed : 0, 0)) { >>> if (gc_type == FG_GC && sec_freed < gc_control->nr_free_secs) >>> goto go_gc_more; >>> - goto stop; >>> - } >>> - >>> - /* FG_GC stops GC by skip_count */ >>> - if (gc_type == FG_GC) { >>> + stop_gc = true; >> >> I guess below condition is for emergency recycle of prefree segments during >> foreground GC, in order to avoid exhausting free sections due to to many >> metadata allocation during CP. >> >> if (free_sections(sbi) <= upper_secs + NR_GC_CHECKPOINT_SECS && >> prefree_segments(sbi)) { >> >> But for common case, free_sections() is close to reserved_segments(), and >> upper_secs + NR_GC_CHECKPOINT_SECS value may be far smaller than free_sections(), >> so checkpoint may not be trggered as expected, IIUC. >> >> So it's fine to just trigger CP in the end of foreground garbage collection? > > My major concern is to avoid unnecessary checkpointing given multiple FG_GC > requests were pending in parallel. And, I don't want to add so many combination > which gives so many corner cases, and feel f2fs_gc() needs to call checkpoint > automatically in the worst case scenario only. Alright. > > By the way, do we just need to call checkpoint here including FG_GC as well? I didn't get it, do you mean? - f2fs_balance_fs() - f2fs_gc() creates prefree segments but not call checkpoint to reclaim - f2fs_balance_fs() - f2fs_gc() - detect prefree segments created by last f2fs_balance_fs, then call f2fs_write_checkpoint to reclaim Or could you please provide a draft patch? :-P Thanks, > > 1832 > 1833 if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0)) { > 1834 /* > 1835 * For example, if there are many prefree_segments below given > 1836 * threshold, we can make them free by checkpoint. Then, we > 1837 * secure free segments which doesn't need fggc any more. > 1838 */ > 1839 if (prefree_segments(sbi)) { > 1840 ret = f2fs_write_checkpoint(sbi, &cpc); > 1841 if (ret) > 1842 goto stop; > 1843 } > 1844 if (has_not_enough_free_secs(sbi, 0, 0)) > 1845 gc_type = FG_GC; > 1846 } > >> >> One other concern is for those path as below: >> - disable_checkpoint >> - ioc_gc >> - ioc_gc_range >> - ioc_resize >> ... > > I think the upper caller should decide to call checkpoint, if they want to > reclaim the prefree likewise f2fs_disable_checkpoint. > >> >> We've passed gc_type as FG_GC, but the demand here is to migrate block in time, >> rather than dirtying blocks, and callers don't expect checkpoint in f2fs_gc(), >> instead the callers will do the checkpoit as it needs. >> >> That means it's better to decouple FG_GC and write_checkpoint behavior, so I >> added another parameter .reclaim_space to just let f2fs_balance_fs() to trigger >> checkpoit in the end of f2fs_gc(). > >> >> Thanks, >> >>> + } else if (gc_type == FG_GC) { >>> + /* FG_GC stops GC by skip_count */ >>> if (sbi->skipped_gc_rwsem) >>> skipped_round++; >>> round++; >>> if (skipped_round > MAX_SKIP_GC_COUNT && >>> - skipped_round * 2 >= round) { >>> - ret = f2fs_write_checkpoint(sbi, &cpc); >>> - goto stop; >>> - } >>> + skipped_round * 2 >= round) >>> + stop_gc = true; >>> } >>> __get_secs_required(sbi, NULL, &upper_secs, NULL); >>> @@ -1901,12 +1898,13 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control) >>> prefree_segments(sbi)) { >>> ret = f2fs_write_checkpoint(sbi, &cpc); >>> if (ret) >>> - goto stop; >>> + stop_gc = true; >>> } >>> go_gc_more: >>> - segno = NULL_SEGNO; >>> - goto gc_more; >>> - >>> + if (!stop_gc) { >>> + segno = NULL_SEGNO; >>> + goto gc_more; >>> + } >>> stop: >>> SIT_I(sbi)->last_victim[ALLOC_NEXT] = 0; >>> SIT_I(sbi)->last_victim[FLUSH_DEVICE] = gc_control->victim_segno; _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel